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, 22 (1), 1-28

Prolactin Response to Suckling and Maintenance of Postpartum Amenorrhea Among Intensively Breastfeeding Nepali Women

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Prolactin Response to Suckling and Maintenance of Postpartum Amenorrhea Among Intensively Breastfeeding Nepali Women

J F Stallings et al. Endocr Res.

Abstract

The aim of the study was to determine the association between PRL responses to suckling and maintenance of postpartum amenorrhea among breastfeeding mothers. Three blood spot samples (5, 30, and 50 min following a timed nursing bout) were collected from 71 intensively breastfeeding Nepali women for PRL determination. Maternal age, BMI (weight/height2), menstrual status, caste, infant age, nursing bout length, and duration of supplementation were recorded at time of sample collection. Independent and paired t tests, linear regression analyses, and general linear models were used to evaluate differences between cycling (n = 36) and amenorrheic (n = 35) women and associations among variables. Logistic regression analyses were used to relate PRL measures to the odds of maintaining lactational amenorrhea. Amenorrheic breastfeeding mothers had higher (P < .001) PRL levels at all 3 collection times than cycling breastfeeding mothers, and PRL levels declined with time since birth (P < 0.05). The odds (OR) of having ceased lactational amenorrhea was significantly higher (OR = 5.0, 95% Cl = 1.3-19.9) among mothers with lower PRL levels (< or = 10 ng/mL) at 50 min post-sucking, and PRL at 50 min showed a significant dose response relationship with menstrual status. The association between 50 min PRL levels and lactational amenorrhea appears to be independent of time postpartum, maternal age, BMI, nursing bout length, and duration of supplementation. Among intensively nursing women, maintenance of elevated PRL levels across the interbout interval increases the odds of maintaining lactational amenorrhea.

PIP: In August 1991, in Nepal, all women aged 19-45 from the Tamang caste (agro-pastoralists of Tibetan origin) and from the Kami caste (low-caste blacksmiths of Aryan origin) who were intensively breast feeding and lived in remote villages in the foothills of the Himalayas were included in a study aiming to examine the association between post-suckling prolactin (PRL) and menstrual status. The study also aimed to determine what PRL response time after suckling best predicts the odds of having resumed menses. There were 36 women whose menses had returned and 35 women who remained amenorrheic. 50-minute post-suckling PRL levels were more linked to menstrual status than 5-minute levels (odds ratio [OR] = 5 vs. 2.1). They (but not 5-minute post-suckling PRL levels) also had a significant dose relationship with menstrual status. During the first year postpartum, PRL levels were significantly higher at all three collection times (5, 30, or 50 minutes) in amenorrheic women than cycling women (p 0.001). PRL levels fell as infant age increased (16 ng/ml for 11 months or less, 13.7 ng/ml for 11-15 months, and 7.4 ng/ml for 15 months; p 0.05). At 50 minutes post-suckling, mothers with PRL levels at or below 10 ng/ml were much more likely to have returned to menses than those with higher levels (OR = 5; p = 0.041). The association between 50-minute PRL levels and lactational amenorrhea were independent of time postpartum, maternal age, body mass index, nursing bout length, and duration of supplementation. The maintenance of high PRL levels across the interbout interval increased the odds of maintaining lactational amenorrhea (p 0.05). In conclusion, intensively nursing women whose PRL levels remain high across the interbout interval are most likely to maintain lactational amenorrhea.

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